Generally, a constant vehicle speed retaining device is provided to reduce fuel consumption by suppressing fluctuations in vehicle speed.
Such a known constant vehicle speed retaining device is disclosed in Japanese Published Patent Application No. 61-6032. In the conventional constant vehicle speed retaining device disclosed in this reference, a switch for cancelling the operation of the device is mounted to a cable member for transmitting a torque of a throttle grip to a throttle valve in a suction system of an engine mounted in the motorcycle. The operation of the constant vehicle speed retaining device may be cancelled by operating the throttle grip. However, as the cancellation switch is generally mounted to the cable member between the throttle grip and the throttle valve, independent wiring must be provided for connecting the cancellation switch to a control circuit as a center of the constant vehicle speed retaining device, necessitating a complicated wiring operation.